This application claims the benefit of the Korean Patent Application No. P2002-07774 filed on Feb. 9, 2002, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly, to a device for cutting a liquid crystal display panel and a method for cutting using the same to separate a unit liquid crystal display panel from the mother substrate.
2. Discussion of the Related Art
In general, a liquid crystal display device displays a desired picture by individually supplying a data signal according to picture information to the liquid crystal cell arranged in a matrix form and controlling light transmittance of the liquid crystal cells.
The liquid crystal display device includes a liquid crystal display panel on which liquid crystal cells of a pixel unit are arranged in a matrix form, and a driver integrated circuit (IC) for driving the liquid crystal cells.
The liquid crystal display panel includes a color filter substrate and a thin film transistor array substrate that are facing into each other and a liquid crystal filled between the color filter substrate and the thin film transistor array substrate.
On the thin film transistor array substrate of the liquid crystal display panel, there are a plurality of data lines for transmitting a data signal supplied from a data driver integrated circuit to the liquid crystal cell and a plurality of gate lines for transmitting a scan signal supplied from a gate driver integrated circuit to the liquid crystal cells. The liquid crystal cells are defined at each portion where the data lines and the gate lines cross each other.
The gate driver integrated circuit sequentially supplies a scan signal to the plurality of gate lines so that the liquid crystal cells arranged in a matrix form are sequentially selected line by line. A data signal is supplied from the data driver integrated circuit to the selected line of the liquid crystal cells.
Meanwhile, a common electrode and a pixel electrode are formed the color filter substrate and the thin film transistor array substrate to face into each other for applying an electric field to the liquid crystal layer.
The pixel electrode is formed by liquid crystal cells on the thin film transistor array substrate, while the common electrode is integrally formed on the entire surface of the color filter substrate.
Accordingly, by controlling a voltage applied to the pixel electrode while a voltage is applied to the common electrode, the light transmittance of the liquid crystal cells is individually controlled.
In order to control the voltage applied to the pixel electrode by each liquid crystal cell, a thin film transistor used as a switching device is formed at each liquid crystal cell.
To improve yield in fabricating a liquid crystal display device, a plurality of thin film transistor array substrates are formed on one large mother substrate, and a plurality of color filter substrates are formed on the other mother substrate. The two mother substrates are the attached to simultaneously form the plurality of liquid crystal display panels. Thus, a process for cutting the liquid crystal display panel into a plurality of unit panels is required.
Cutting the liquid crystal display panel is performed by a scribing process for forming a scribing line on the surface of the mother substrate with a pen made of diamond having a hardness higher than that of glass and a breaking process for cutting by applying a mechanical force along the scribing line.
The cutting process will now be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic plane view showing a unit liquid crystal display panel formed with a thin film transistor array substrate 1 and a color filter substrate 2 attached to face into each other.
In FIG. 1, the liquid crystal display panel 10 includes a picture display unit 13 having a plurality of liquid crystal cells arranged in a matrix form, a gate pad unit 14 connected to a plurality of gate lines of the picture display unit 13, and a data pad unit 15 connected to the gate pad unit 14 and a plurality of data lines.
The gate pad unit 14 and the data pad unit 15 are formed at the marginal portion of the thin film transistor array substrate 1. The portion does not overlap the color filter substrate 2.
The gate pad unit 14 supplies a scan signal supplied from the gate driver integrated circuit to the gate lines of the picture display unit 13. The data pad unit 15 supplies picture information supplied from the data driver integrated circuit to the data lines of the picture display unit 13.
The data lines receiving the picture information and the gate lines receiving the scan signal are disposed to be crossed orthogonally on the thin film transistor array substrate 1 of the picture display unit 13. At the crossed portion, a thin film transistor is formed for switching the liquid crystal cells, and a pixel electrode is formed to be connected to the thin film transistor for driving the liquid crystal cell. Further, a protective film is formed at the entire surface to protect the electrode and the thin film transistor.
At the color filter substrate 2 of the picture display unit 13, a plurality of color filters are coated to be separated by cell regions with a black matrix, and a common transparent electrode to the pixel electrode are formed at the thin film transistor array substrate 1.
A cell gap is formed between the thin film transistor array substrate 1 and the color filter substrate 2 so that the two substrates are spaced apart and face into each other. The thin film transistor array substrate 1 and the color filter substrate 2 are attached by a sealant (not shown) formed at the exterior of the picture display unit 13. A liquid crystal layer (not shown) is formed at the space between the thin film transistor array substrate 1 and the color filter substrate 2.
FIG. 2 is a cross-sectional view showing a plurality of unit liquid crystal display panels formed in the first mother substrate having the thin film transistor array substrates 1 and the second mother substrate with the color filter substrate 2.
As shown in FIG. 2, a plurality of unit panels are formed in such a manner that one side of the thin film transistor array substrate 1 is protruded as much as a dummy region 31.
This is because the gate pad unit 14 and the data pad unit 15 are formed at the marginal portion where the thin film transistor array substrate 1 and the color filter substrate 2 do not overlap.
Thus, the color filter substrate 2 formed on the second mother substrate 30 is formed to be isolated as much as dummy regions 31 corresponding to the area that the thin film transistor array substrates 1 formed on the first mother substrate 20 are protruded.
Each unit panel is disposed at the first and second mother substrates 20 and 30 so that the first and the second mother substrates 20 and 30 are used at the maximum. Depending on a model, the unit liquid crystal display panels are generally formed to be isolated as much as the dummy region 32.
After the first mother substrate 20 where the thin film transistor array substrates 1 are formed and the second mother substrate 30, where the color filter substrates 2 are formed, are attached each other, the liquid crystal display panels are individually cut through the scribing process and the breaking process. The dummy regions 31 formed at the region where the color filter substrates 2 of the second mother substrate 30 are isolated. The dummy region 32 isolating the unit panels are simultaneously removed.
The cutting process to the unit panels will now be described with reference to FIGS. 3A to 3J.
As shown in FIG. 3A, the first mother substrate 20 and the second mother substrate 30 are loaded on a first table 33.
Next, as shown in FIG. 3B, the first table 33 is moved in one direction to sequentially form a plurality of first scribing lines 42 on the first mother substrate 20 with a cutting wheel 41.
After first and second mother substrates 20 and 30 in FIG. 3C are rotated by 90xc2x0, the first table 33 is moved to its original position to sequentially form a plurality of second scribing lines 43 on the surface of the first mother substrate 20 through the cutting wheel 41.
FIG. 3D illustrates the first and second mother substrates 20 and 30, which are overturned and loaded on a second table 34. While the second table 34 is moved in one direction, the second mother substrate 30 is pressed by a breaking bar 44 along the second scribing lines 43 so that a crack is transmitted on the first mother substrate 20.
Next, as shown in FIG. 3E, second and first mother substrates 30 and 20 are rotated by 90xc2x0. While the second table 34 is moved to its original position, the second mother substrate 30 is pressed by the breaking bar 44 along the first scribing lines 42, so that a crack is transmitted on the first mother substrate 20.
As shown in FIG. 3F, the second and first substrates 30 and 20 are loaded on a third table 35. A plurality of third scribing lines 46 are sequentially formed on the surface of the second mother substrate 30 with a cutting wheel 45 by moving the third table 35 in one direction.
Thereafter, the second and first mother substrates 30 and 20 are rotated by 90xc2x0, as shown in FIG. 3G. A plurality fourth scribing lines 47 are sequentially formed on the surface of the second mother substrate 30 with the cutting wheel 45 by moving the third table 35 to its original position.
As shown in FIG. 3H, second and first mother substrates 30 and 20 are overturned and loaded on the fourth table 36. The first mother substrate 20 is pressed by a breaking bar 48 along the fourth scribing line 47 by moving the fourth table 36 in one direction, so that a crack is transmitted on the second mother substrate 30.
Next, the first and second mother substrates 20 and 30 are rotated by 90xc2x0, as shown in FIG. 3I. The first mother substrate 20 is pressed by the breaking bar 48 along the third scribing line 46 by moving the fourth table 36 to its original position, so that a crack is transmitted on the second mother substrate 30.
As shown in FIG. 3J, as the crack is transmitted on first and second mother substrates 20 and 30 along first through fourth scribing lines 42, 43, 46, and 47, unit panels are selectively unloaded by using a vacuum gripper 49 and conveyed to the equipment for next processes.
As mentioned above, in the conventional cutting device and cutting processes for the unit panel, scribing is performed four times and breaking is performed four times through four rotation processes and two overturning processes.
Thus, two scribing units including a rotating unit and two breaking units including a rotating unit and an overturning unit are required. These equipments would occupy much space in the working place. Thus, an installation expense and a space of the equipment are wasted.
In addition, much time is required for the scribing and breaking processes, resulting in a low productivity.
Accordingly, the present invention is directed to a device for cutting a liquid crystal display panel and a method for cutting using the same that substantially obviates one or more of problems due to limitations and disadvantages of the related art.
Another object of the present invention is to provide a device for cutting a liquid crystal display panel and a method for cutting using the same that is capable of minimizing the number of rotations and overturnings for cutting the unit panels from the mother substrate.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a device for cutting a liquid crystal display panel includes a first scribing unit for forming a first scribing line at first and second mother substrates by using first and pressing at least a portion of the first scribing line with a first roll, a second scribing unit for forming a second scribing line at the first and second mother substrates by using third and fourth wheels and pressing at least a portion of the second scribing line with a second roll, and a first rotating unit for rotating the first and second mother substrates to form the second scribing line.
In another aspect of the present invention, a device for cutting a liquid crystal display panel includes a first scribing unit for loading and holding first and second mother substrates between the first and second tables, forming a first scribing line on the first and second mother substrates with first and second wheels, and cutting the first and second mother substrates by moving the first and second tables, a first rotating unit for rotating the first and second mother substrates by 90xc2x0, and a second scribing unit for loading and holding the first and second mother substrates between the third and fourth tables, forming a second scribing line on first and second mother substrates with the third and fourth wheels to cut the first and second mother substrates by moving the third and fourth tables.
In another aspect of the present invention, a method for cutting a liquid crystal display panel includes forming a first scribing line at first and second mother substrates, pressing at least a portion of the first scribing line with a first roll to cut the first and second mother substrates, forming a second scribing line at the first and second mother substrates, and pressing at least a portion of the second scribing line with a second roll to cut the first and second mother substrates.
In a further aspect of the present invention, a method for cutting a liquid crystal display panel includes loading and holding first and second mother substrates between the first and second tables, forming a first scribing line at first and second mother substrates, cutting the first and second mother substrates by moving the first and second tables, loading and holding the first and second mother substrates between the third and fourth tables, forming a second scribing line at the first and second mother substrates, and cutting the first and second mother substrates by moving the third and fourth tables.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.